Pleiotropic function of the oca2 gene underlies the evolution of sleep loss and albinism in cavefish
Pleiotropic function of the oca2 gene underlies the evolution of sleep loss and albinism in cavefish
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DOI：
10.1016/j.cub.2021.06.077
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发表时间：
2021-08-23
期刊：
影响因子：
9.2
通讯作者：
Kowalko, Johanna E.
中科院分区：
文献类型：
--
作者：
O'Gorman, Morgan;Thakur, Sunishka;Kowalko, Johanna E.
对新环境的适应通常涉及多种形态、生理和行为特征的进化。多性状进化的一个突出例子是在洞穴动物中反复进化的一套性状，包括眼睛的退化，色素沉着的丧失和非视觉感官系统的增强。（1，2）墨西哥四，Astyanax mexicanus，由居住在墨西哥至少30个洞穴的鱼和居住在墨西哥和德克萨斯州南部河流的祖先般的水面鱼组成。(3)洞穴A墨西哥鱼与水面鱼类是可交配的，并且已经进化出许多特征，包括色素减少、眼睛丧失和行为改变。(4-6)为了定义不同洞穴进化性状之间的关系，我们表型208表面洞穴F2杂交鱼的许多形态和行为特征。我们发现有色和白化病杂交鱼之间的睡眠差异，提高了这些特征共享遗传基础的可能性。在洞穴鱼和其他物种中，眼皮肤白化病2（oca2）的突变导致白化病。(7-2)oca2基因突变的水面鱼表现出白化病和睡眠减少。此外，当携带这种工程突变的水面鱼与具有oca2天然突变的独立进化的白化病洞穴鱼种群杂交时，oca2中的这种突变不能补充睡眠丧失。野生洞穴鱼类和表层鱼类的oca2基因座分析表明，oca2基因在3个洞穴种群中均处于正选择状态。总之，这些发现确定了oca2作为一种新的睡眠调节因子，并表明oca2的多效性功能是白化病和睡眠丧失的适应性进化的基础。
Adaptation to novel environments often involves the evolution of multiple morphological, physiological, and behavioral traits. One striking example of multi-trait evolution is the suite of traits that has evolved repeatedly in cave animals, including regression of eyes, loss of pigmentation, and enhancement of non-visual sensory systems.(1,2) The Mexican tetra, Astyanax mexicanus, consists of fish that inhabit at least 30 caves in Mexico and ancestral-like surface fish that inhabit the rivers of Mexico and southern Texas.(3) Cave A. mexicanus are interfertile with surface fish and have evolved a number of traits, including reduced pigmentation, eye loss, and alterations to behavior.(4-6) To define relationships between different cave-evolved traits, we phenotyped 208 surface-cave F2 hybrid fish for numerous morphological and behavioral traits. We found differences in sleep between pigmented and albino hybrid fish, raising the possibility that these traits share a genetic basis. In cavefish and other species, mutations in oculocutaneous albinism 2 (oca2) cause albinism.(7-2) Surface fish with mutations in oca2 displayed both albinism and reduced sleep. Further, this mutation in oca2 fails to complement sleep loss when surface fish harboring this engineered mutation are crossed to independently evolved populations of albino cavefish with naturally occurring mutations in oca2. Analysis of the oca2 locus in wild-caught cave and surface fish suggests that oca2 is under positive selection in 3 cave populations. Taken together, these findings identify oca2 as a novel regulator of sleep and suggest that a pleiotropic function of oca2 underlies the adaptive evolution of albinism and sleep loss.